1. Field of the Invention
The invention relates to addition-crosslinking silicone resin compositions and to the use thereof.
2. Background Art
Addition-crosslinking siloxanes have long been known in the area of elastomers, for example RTV-2 rubber, liquid rubber and addition-crosslinking hot rubber. Characteristically, these materials, when cured, have hardnesses in the Shore A range, or less than 20 Shore D. These crosslinkable materials are formulations comprising at least 2 components, which separately contain Si—H and Si-vinyl crosslinking functionalities.
U.S. published application 2002/0161140 A1 describes an addition-crosslinking phenylsilicone resin composition, the cured silicone resin having a hardness greater than Shore D 60. However, curing temperatures of 200° C. are required in order to avoid long curing times. The use of such compositions with heat-sensitive components such as electronic components or by molding in molds of organic polymer material is therefore impossible.
EP 1 249 873 A2 discloses the use of silicone resins which have a Shore A hardness in the range from 50 to 90 for the casting of “light emitting devices”, so-called LEDs. A Shore A hardness in the region of 90 corresponds approximately to a Shore D hardness in the region of 40.